Mapping Groundwater Contamination around a Dumpsite in Benin City, Nigeria Using VLF-EM Method

Abstract

An electromagnetic survey was used to delineate conductive and non conductive zones in order to accurately locate electrical resistivity tomography profiles at Ikhueniro refuse dumpsite. The survey comprised four roughly N – S, and E – W direction, very low frequency electromagnetic (VLF-EM) profiles around the perimeter of refuse dumpsite where contaminants/conductive bodies were observed using resistivity imaging and soil analysis method in a previous study. The Fraser and the Karous-Hjelt filters were used in the interpretation of the VLF-EM field data. The data inversion was carried out using a 2-D code which was constrained using previous resistivity survey. The results of the resistivity models calculated from the pseudosections indicate the presences of low resistivity zone up to a depth of 50 m within the subsurface that is in a good agreement with the results obtained from the previous resistivity imaging survey which indicated leachate contamination at the refuse dumpsite.